[PATCH] D23296: [ValueTracking] Improve ValueTracking on left shift with nsw flag

[Li Huang via llvm-commits]

lihuang updated this revision to Diff 68927.
lihuang added a comment.

Should clear KnownZero and KnownOne bits when there is conflicts to allow propagation of undef. Changed the code in computeKnownBitsFromShiftOperator to have the same logic as that at the end of this function.


https://reviews.llvm.org/D23296

Files:
  lib/Analysis/ValueTracking.cpp
  test/Analysis/ValueTracking/known-signbit-shift.ll

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